If the transaction is complete then it should have unlocked on its own. Sometimes it is slow though. You can try changing the password on the account, or re-entering your address data. The goal is to force the account to re-save things which updates it. That often resolves the issue.
If you are unable to fix it on your own you can give Billing and Account Support a call when they open on Sunday (fastest way) or submit a ticket (may take a few days). http://us.battle.net/support/en/article/contact
(has info on submitting a ticket as well as phone numbers and support hours)
Some tips for calling:
1. The phone lines are always full these days (They support all of D3, WoW, and Starcraft). Spam re-dial immediately when you hear the queue full message until you get in queue and then stay there!
2. Cell phones hate being on hold and can disconnect. Use a land line (free in the US) or Skype (free to download and call them with anywhere in the world).
3. Be prepared for a 45 min + wait on hold
4. Be prepared to prove your identity by answering questions or giving Battle.net game keys
5. If you get it resolved on the phone, remember to cancel any tickets you have in the system to reduce the backlog there.